It sounds like your powertrain control module has internally failed causing the idle speed motor to work all the time even when it shouldnt including with the engine off......Unplug the idle control actuator and if idle drops then replace PCM. Let me know if you have questions, thanks.
Yep, you can reply at anytime even after you accept. Here is a picture of the PCM, let me know if you have questions. I'd get a used one to save money, you can go to www.car-parts.com to order it. Let me know if you have questions. Thanks